[PATCH] Keys: Fix key management syscall interface bugs

This fixes five bugs in the key management syscall interface:

 (1) add_key() returns 0 rather than EINVAL if the key type is "".

     Checking the key type isn't "" should be left to lookup_user_key().

 (2) request_key() returns ENOKEY rather than EPERM if the key type begins
     with a ".".

     lookup_user_key() can't do this because internal key types begin with a
     ".".

 (3) Key revocation always returns 0, even if it fails.

 (4) Key read can return EAGAIN rather than EACCES under some circumstances.

     A key is permitted to by read by a process if it doesn't grant read
     access, but it does grant search access and it is in the process's
     keyrings. That search returns EAGAIN if it fails, and this needs
     translating to EACCES.

 (5) request_key() never adds the new key to the destination keyring if one is
     supplied.

     The wrong macro was being used to test for an error condition: PTR_ERR()
     will always return true, whether or not there's an error; this should've
     been IS_ERR().

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Linus Torvalds <torvalds@osdl.org>

security/keys/keyctl.c

@@ -49,9 +49,6 @@ asmlinkage long sys_add_key(const char __user *_type,
 		goto error;
 	type[31] = '\0';
 
-	if (!type[0])
-		goto error;
-
 	ret = -EPERM;
 	if (type[0] == '.')
 		goto error;
@@ -144,6 +141,10 @@ asmlinkage long sys_request_key(const char __user *_type,
 		goto error;
 	type[31] = '\0';
 
+	ret = -EPERM;
+	if (type[0] == '.')
+		goto error;
+
 	/* pull the description into kernel space */
 	ret = -EFAULT;
 	dlen = strnlen_user(_description, PAGE_SIZE - 1);
@@ -362,7 +363,7 @@ long keyctl_revoke_key(key_serial_t id)
 
 	key_put(key);
  error:
-	return 0;
+	return ret;
 
 } /* end keyctl_revoke_key() */
 
@@ -685,6 +686,8 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 			goto can_read_key2;
 
 		ret = PTR_ERR(skey);
+		if (ret == -EAGAIN)
+			ret = -EACCES;
 		goto error2;
 	}
 

security/keys/request_key.c

@@ -405,7 +405,7 @@ struct key *request_key_and_link(struct key_type *type,
 		key_user_put(user);
 
 		/* link the new key into the appropriate keyring */
-		if (!PTR_ERR(key))
+		if (!IS_ERR(key))
 			request_key_link(key, dest_keyring);
 	}